1. Field of the Invention
The present invention relates in general to safety devices of wheeled motor vehicle, and more particularly to an air-bag device which, upon a vehicle collision, expands instantly for protecting a passenger of the vehicle. More specifically, the present invention is concerned with an air-bag device which is designed to exhibit a marked passenger protection effect even when it is made compact in size.
2. Description of the Prior Art
In order to clarify the task of the present invention, one of the conventional air-bag devices hitherto proposed will be outlined with reference to FIGS. 19 and 20 of the accompanying drawings, which is disclosed in Japanese Utility Model Second Provisional Publication No. 61-11084.
As is shown in FIG. 19, the air-bag device 6 comprises an air-bag proper 1, an inflator 3 having gas flow openings 2 exposed to flow gas into the air-bag to the interior of the air-bag proper 1, an igniter 5 for actuating the inflator 3 and a trimmed cover 4 covering the air-bag proper 1 in a folded up condition. The gas flow openings 2 are equal in size and shape and arranged at equally spaced intervals.
As is seen from FIG. 20, in practical use, the air-bag device 6 is mounted to a center pad 10 of a steering wheel 7. In operation, the inflator 3 generates gas and thus inflates the air-bag proper 1. Due to the inflation of the air-bag proper 1, the trimmed cover 4 is opened or broken allowing a full inflation of the bag 1 outside of the trimmed cover 4.
However, the conventional air-bag device 6 has the following drawbacks due to its inherent construction.
Upon inflation of the air-bag proper 1, it comes to contact with the passenger 8, and the gas in the bag 1 is forced to flow upward as indicated by the thick arrow causing the upper part of the bag 1 to suffer a higher internal pressure. This causes the air-bag 1 thus expanded to shift upward from the center position of the steering wheel 7. Furthermore, in a severe case, such shifting of the expanded-bag 1 induces deformation of a spoke 9 of the steering wheel 7 as shown by a broken line in FIG. 20. Thus, a larger air-bag proper has been hitherto used for dealing with such phenomena. Of course, enlargement of the air-bag proper induces a bulky construction of the air-bag device and thus deteriorates the external appearance of the same.